Mount RAW Pool Image with ZFS on Linux

Suppose you have backed up a ZFS pool with dd so you want to get some data from rpool.img now. Look at disk-image-mount-partition for more ways to mount patitions.

Mounting

  1. Mount image as loop device
    # losetup /dev/loop0 rpool.img
  2. List partitions in loop
    # kpartx -l /dev/loop0
loop0p1 : 0 44019712 /dev/loop0 2048
loop0p9 : 0 16384 /dev/loop0 44021760
  3. Create device mappings of partitions
    # kpartx -av /dev/loop0
add map loop0p1 (252:0): 0 44019712 linear 7:0 2048
add map loop0p9 (252:1): 0 16384 linear 7:0 44021760
  4. Create mount point
    # mkdir /mnt/misa
  5. Try import the ZFS pool, but it will definitely fail because 1) my rpool.img is readonly 2) rpool is already used on my system
    # zpool import -R /mnt/misa -d /dev/mapper
   pool: rpool
     id: 3090542417815288870
  state: ONLINE
 status: Some supported features are not enabled on the pool.
 action: The pool can be imported using its name or numeric identifier, though
        some features will not be available without an explicit 'zpool upgrade'.
 config:

        rpool       ONLINE
          loop0     ONLINE
  6. With the id from previous result, we can import this pool with a new name misa
    # zpool import -o readonly=on -f -d /dev/mapper 3090542417815288870 misa -R /mnt/misa
  7. Done
    # zpool status
  pool: misa
 state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
        still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
        the pool may no longer be accessible by software that does not support
        the features. See zpool-features(5) for details.
  scan: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        misa        ONLINE       0     0     0
          loop0     ONLINE       0     0     0

errors: No known data errors

# zpool list
NAME    SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
misa   20.9G   716M  20.2G         -     0%     3%  1.00x  ONLINE  /mnt/misa

# zfs list misa -r
NAME                 USED  AVAIL  REFER  MOUNTPOINT
misa                 716M  19.5G    96K  /mnt/misa
misa/ROOT            533M  19.5G    96K  none
misa/ROOT/ubuntu     533M  19.5G   533M  /mnt/misa
misa/home            996K  19.5G    96K  /mnt/misa/home
misa/home/root       900K  19.5G   900K  /mnt/misa/root
misa/srv              96K  19.5G    96K  /mnt/misa/srv
misa/var             179M  19.5G    96K  /mnt/misa/var
misa/var/cache       174M  19.5G   174M  /mnt/misa/var/cache
misa/var/lib        3.81M  19.5G    96K  /mnt/misa/var/lib
misa/var/lib/mysql  3.72M  19.5G  3.72M  /mnt/misa/var/lib/mysql
misa/var/log        1.09M  19.5G  1.09M  /mnt/misa/var/log
misa/var/spool        96K  19.5G    96K  /mnt/misa/var/spool
misa/var/tmp         120K  19.5G   120K  /mnt/misa/var/tmp

Unmounting

  1. Export the pool
    # zpool export misa
  2. Disconnect the device map files using kpartx
    # kpartx -dv /dev/loop0
del devmap : loop0p9
del devmap : loop0p1
  3. Unload loop device
    # losetup -d /dev/loop0

See Alsos

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